Processing of flexible substrates, such as plastic films or foils, is in high demand in the packaging industry, semiconductor industries and other industries. Processing may consist of coating of a flexible substrate with a desired material, such as a metal, semiconductors and dielectric materials, etching and other processing steps conducted on a substrate for the desired applications. Systems performing this task generally include a processing drum, e.g., a cylindrical roller, coupled to a processing system for transporting the substrate, and on which at least a portion of the substrate is processed. Roll-to-roll coating systems can, thereby, provide a high throughput system.
Typically, a coating process, such as a chemical evaporation process or a thermal evaporation process, can be utilized for depositing thin layers of materials onto flexible substrates. Roll-to-roll deposition systems are understood in that a flexible substrate of considerable length, such as at least several kilometers, is uncoiled from a flexible substrate storage spool, coated with a thin-film, and recoiled again on another spool. Roll-to-roll deposition systems are also experiencing a strong increase in demand in the display industry and the photovoltaic (PV) industry. For example, touch panel elements, flexible displays, and flexible PV modules result in an increasing demand for depositing suitable layers in Roll-to-Roll coaters, particularly with low manufacturing costs.
Damages to the substrate may reduce the usability and/or value of the substrate. In particular, particles may be located on the flexible substrate and may thus pollute the substrate's surface. Even worse, if the flexible substrate is wound up after the deposition, the dirt particles may be included in between the layers of the flexible substrate on the spool. They may not only cause a pinhole or the like at their position, they may also cause damages to adjacent layers which are pressed against the particles in the winding process.
Therefore, there is a need in the art for an efficient cleaning apparatus and method when processing flexible substrates, such as OLED structures, semiconductor structures and other modern more sophisticated devices to ensure substrate deposition quality is enhanced.